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Detecting referral and selection bias by the anonymous linkage of practice, hospital and clinic data using Secure and Private Record Linkage (SAPREL): case study from the evaluation of the Improved Access to Psychological Therapy (IAPT) service

Detecting referral and selection bias by the anonymous linkage of practice, hospital and clinic data using Secure and Private Record Linkage (SAPREL): case study from the evaluation of the Improved Access to Psychological Therapy (IAPT) service
Detecting referral and selection bias by the anonymous linkage of practice, hospital and clinic data using Secure and Private Record Linkage (SAPREL): case study from the evaluation of the Improved Access to Psychological Therapy (IAPT) service
Background:The evaluation of demonstration sites set up to provide improved access to psychological therapies (IAPT) comprised the study of all people identified as having common mental health problems (CMHP), those referred to the IAPT service, and a sample of attenders studied in-depth. Information technology makes it feasible to link practice, hospital and IAPT clinic data to evaluate the representativeness of these samples. However, researchers do not have permission to browse and link these data without the patients' consent.

Objective:To demonstrate the use of a mixed deterministic-probabilistic method of secure and private record linkage (SAPREL) - to describe selection bias in subjects chosen for in-depth evaluation.

Method: We extracted, pseudonymised and used fuzzy logic to link multiple health records without the researcher knowing the patient's identity. The method can be characterised as a three party protocol mainly using deterministic algorithms with dynamic linking strategies; though incorporating some elements of probabilistic linkage. Within the data providers' safe haven we extracted: Demographic data, hospital utilisation and IAPT clinic data; converted post code to index of multiple deprivation (IMD); and identified people with CMHP. We contrasted the age, gender, ethnicity and IMD for the in-depth evaluation sample with people referred to IAPT, use hospital services, and the population as a whole.

Results: The in IAPT-in-depth group had a mean age of 43.1 years; CI: 41.0 - 45.2 (n = 166); the IAPT-referred 40.2 years; CI: 39.4 - 40.9 (n = 1118); and those with CMHP 43.6 years SEM 0.15. (n = 12210). Whilst around 67% of those with a CMHP were women, compared to 70% of those referred to IAPT, and 75% of those subject to in-depth evaluation (Chi square p < 0.001). The mean IMD score for the in-depth evaluation group was 36.6; CI: 34.2 - 38.9; (n = 166); of those referred to IAPT 38.7; CI: 37.9 - 39.6; (n = 1117); and of people with CMHP 37.6; CI 37.3-37.9; (n = 12143).

Conclusions:The sample studied in-depth were older, more likely female, and less deprived than people with CMHP, and fewer had recorded ethnic minority status. Anonymous linkage using SAPREL provides insight into the representativeness of a study population and possible adjustment for selection bias.

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de Lusignan, Simon
d3a4897a-91dd-4880-b273-f92c2fe6c42f
Navarro, Rob
d8981b9c-4c74-4ea5-bfc8-10880ce30df4
Chan, Tom
ec5cfb49-0fd8-4aca-b485-8baec9081dd1
Parry, Glenys
1a31023a-92f2-4b12-96e6-61c83409d10b
Dent-Brown, Kim
45d9edbe-58f9-4975-b719-83efedb8a7ca
Kendrick, Tony
c697a72c-c698-469d-8ac2-f00df40583e5
de Lusignan, Simon
d3a4897a-91dd-4880-b273-f92c2fe6c42f
Navarro, Rob
d8981b9c-4c74-4ea5-bfc8-10880ce30df4
Chan, Tom
ec5cfb49-0fd8-4aca-b485-8baec9081dd1
Parry, Glenys
1a31023a-92f2-4b12-96e6-61c83409d10b
Dent-Brown, Kim
45d9edbe-58f9-4975-b719-83efedb8a7ca
Kendrick, Tony
c697a72c-c698-469d-8ac2-f00df40583e5

de Lusignan, Simon, Navarro, Rob, Chan, Tom, Parry, Glenys, Dent-Brown, Kim and Kendrick, Tony (2011) Detecting referral and selection bias by the anonymous linkage of practice, hospital and clinic data using Secure and Private Record Linkage (SAPREL): case study from the evaluation of the Improved Access to Psychological Therapy (IAPT) service. BMC Medical Informatics and Decision Making, 11, 61. (doi:10.1186/1472-6947-11-61).

Record type: Article

Abstract

Background:The evaluation of demonstration sites set up to provide improved access to psychological therapies (IAPT) comprised the study of all people identified as having common mental health problems (CMHP), those referred to the IAPT service, and a sample of attenders studied in-depth. Information technology makes it feasible to link practice, hospital and IAPT clinic data to evaluate the representativeness of these samples. However, researchers do not have permission to browse and link these data without the patients' consent.

Objective:To demonstrate the use of a mixed deterministic-probabilistic method of secure and private record linkage (SAPREL) - to describe selection bias in subjects chosen for in-depth evaluation.

Method: We extracted, pseudonymised and used fuzzy logic to link multiple health records without the researcher knowing the patient's identity. The method can be characterised as a three party protocol mainly using deterministic algorithms with dynamic linking strategies; though incorporating some elements of probabilistic linkage. Within the data providers' safe haven we extracted: Demographic data, hospital utilisation and IAPT clinic data; converted post code to index of multiple deprivation (IMD); and identified people with CMHP. We contrasted the age, gender, ethnicity and IMD for the in-depth evaluation sample with people referred to IAPT, use hospital services, and the population as a whole.

Results: The in IAPT-in-depth group had a mean age of 43.1 years; CI: 41.0 - 45.2 (n = 166); the IAPT-referred 40.2 years; CI: 39.4 - 40.9 (n = 1118); and those with CMHP 43.6 years SEM 0.15. (n = 12210). Whilst around 67% of those with a CMHP were women, compared to 70% of those referred to IAPT, and 75% of those subject to in-depth evaluation (Chi square p < 0.001). The mean IMD score for the in-depth evaluation group was 36.6; CI: 34.2 - 38.9; (n = 166); of those referred to IAPT 38.7; CI: 37.9 - 39.6; (n = 1117); and of people with CMHP 37.6; CI 37.3-37.9; (n = 12143).

Conclusions:The sample studied in-depth were older, more likely female, and less deprived than people with CMHP, and fewer had recorded ethnic minority status. Anonymous linkage using SAPREL provides insight into the representativeness of a study population and possible adjustment for selection bias.

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More information

Published date: October 2011
Organisations: Primary Care & Population Sciences

Identifiers

Local EPrints ID: 353920
URI: http://eprints.soton.ac.uk/id/eprint/353920
PURE UUID: b6af18b9-f296-4225-9a64-13276fd27963
ORCID for Tony Kendrick: ORCID iD orcid.org/0000-0003-1618-9381

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Date deposited: 25 Jun 2013 09:39
Last modified: 15 Mar 2024 02:59

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Contributors

Author: Simon de Lusignan
Author: Rob Navarro
Author: Tom Chan
Author: Glenys Parry
Author: Kim Dent-Brown
Author: Tony Kendrick ORCID iD

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